In an active-matrix type liquid crystal display device, in order to improve optical diffusion characteristics of a reflective electrode, an organic material film with projections and depressions is formed as a primer film of the reflective electrode in a pixel region, and the reflective electrode is formed on the primer film (IDP:In-cell Diffusing Reflector). In the case of forming a contact-hole in a gate insulating film of a thin film transistor TFT), in order to eliminate a photolithography process of the contact-hole, the contact-hole is successively formed in the gate insulating film when the contact-hole is formed in the organic material film of IDR (Hatta et al, ‘A novel 5-mask top-gate TFT process for reflective LCD panels’ Digest of technical papers AM-LCD 02, p 207-210).
The method will be described with reference to FIG. 6.
FIGS. 6(a) to 6(d) are sectional views showing a conventional method for manufacturing a liquid crystal display device. First, as shown in FIG. 6(a), for example, a chrome film is deposited on a glass substrate 100, a light shield film 108 is formed by leaving the chrome film in a portion corresponding to a wiring region by a photolithography process and etching process. Then, a silicon oxide film 101 is formed on the glass substrate 100 and the light shield film 108.
Next, an ITO (Indium-Tin Oxide) film 102 and a metal film 103 are successively formed on the silicon oxide film 101, and an opening portion is formed in the gate region by the photolithography process and etching process. Then, an amorphous silicon (a-Si) film 104 and silicon nitride film 105 are successively formed on the metal film 103 having the opening portion, and are left in the gate region by the photolithography process and etching process.
A silicon nitride film 106 that is a gate insulating film is formed on the entire surface of the substrate. A metal film for a gate electrode is further formed on the film 1066, and a gate electrode 107 is formed in the gate region by the photolithography process and etching process.
Next, as shown in FIG. 6(b), an organic material film 109 for IDR is formed, and projections and depressions are formed on the surface of the organic material film 109. The projections and depressions are formed by, for example, forming the first-layer organic material film, performing exposures on the film while varying the intensity of light with place so as to leave the film in the shape of islands, and then forming the second-layer organic material film thereon.
Then, as shown in FIG. 6(c), the silicon nitride film 106 is subjected to dry etching by plasma 110 to form a contact-hole of the gate insulating film. Subsequently, as shown in FIG. 6(d), a metal film is deposited in the reflective region to form a reflective electrode 111, and the metal film 103 is etched using the reflective electrode 111 as a mask.